* A Dietary Supplement Magnesium Citrate, provided By Douglas Laboratories, supplies 150 mg of elemental magnesium from bioavailable magnesium citrate in each convenient capsule. Functions Magnesium plays an essential role in a wide range of fundamental cellular reactions. More than 300 enzymes require magnesium as a cofactor. Complexed with ATP, the main carrier of metabolic energy in the body, magnesium is essential for all biosynthetic processes: glycolysis, formation of c-AMP, energy-dependent membrane transport, transmission of genetic code for protein synthesis, and muscle function. Magnesium is involved in maintaining already normal heart function and blood pressure